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Do you mean that you get no results when searching non-English content?

This issue occurs because the language setting that is used to query the SharePoint site content is not same as the language setting that is used to index the crawl result. You could get more information from below article:

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If you think my suggestion is helpful, you could mark it as an answer.

Best regards,

Allen Bai

Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact
tnmff@microsoft.com.

SharePoint Server 2019 has been released, you can click
here to download it.
Click here to learn new features. Visit the dedicated
forum to
share, explore and talk to experts about SharePoint Server 2019.